The industrial standards process has generally been recognized as a permissible form of cooperation among otherwise competing enterprises. By promoting operational compatibility and apples-to-apples comparison of products and services, the standards process can lead to enhanced consumer choice, greater competition, and increased technological innovation. However, the possibility exists that a larger enterprise having an established market presence might only selectively activate certain features of an agreed-upon standard in order to obtain an advantage over market entrants or smaller competitors. For example, the larger enterprise might choose to impose certain conditions, such as bundling conditions, on the sale of a key system component before activating the supposedly “standard” features within that key system component. Purchasers of the key system component are thereby “forced” to purchase any complementary system components from that same larger enterprise, much to the detriment of market entrants and smaller competitors who relied on the existence of the agreed-upon standard in developing their own complementary components. At least in part, the present patent specification relates to an instance of this “selective standards activation” scenario that might be found, either presently or prospectively, in the medical imaging industry.
The DICOM standard (Digital Imaging and Communications in Medicine) is defined and maintained by the National Electrical Manufacturers Association, and is directed to providing a common framework for the acquisition, transmission, archiving, retrieval, and presentation of medical images of the human body and related patient data for a variety of imaging modalities and environments. As discussed in Horii, “A Nontechnical Introduction to DICOM,” RadioGraphics 1997:1297-1309 (RSNA 1997), the DICOM standard is highly adaptable and continues to grow to accommodate advances in medical imaging technology. According to Horii, the fact that many of the medical imaging equipment manufacturers are global corporations has sparked considerable international interest in DICOM, with both European and Japanese standards organizations adopting substantial portions of DICOM. The DICOM standard is maintained and extended by the DICOM Standards Committee, which is an international, multi-specialty committee.
Currently, the DICOM standard consists of sixteen published parts, PS 3.1-2003 through PS 3.16-2003, describing different aspects of the DICOM standard. By way of example, the first published part is a 20-page document that can be fully cited as “National Electrical Manufacturers Association, Digital Imaging and Communications in Medicine (DICOM), PS 3.1-2003 Part 1: Introduction and Overview, (NEMA 2003).” This document can more briefly be cited as “PS 3.1-2003: Introduction and Overview,” “PS 3.1-2003,” or, most simply, “PS 3.1,” it being understood that the latter is a reference to the current year, a past year, or a group of years according to the context. Among other published parts of the DICOM standard relevant to the present disclosure are the third part, “PS 3.3-2003: Information Object Definitions,” the fourth part, “PS 3.4-2003: Service Class Specifications,” the sixth part, “PS 3.6-2003: Data Dictionary,” and the sixteenth part, “PS 3.16-2003: Content Mapping Resource.”
Recent additions to the DICOM standard have been made to accommodate the field of computer-aided diagnosis (CAD) in which specialized computer programs analyze medical images to detect anatomical abnormalities, or lesions, therein. Sometimes used interchangeably with the term computer-aided diagnosis are the terms computer-aided detection, computer-assisted diagnosis, or computer-assisted detection. The outputs of CAD systems, generally referred to herein as CAD results, are sets of information sufficient to communicate the locations of anatomical abnormalities, or lesions, in a medical image, and can also include other information such as the type of lesion, degree of suspiciousness, and the like.
Examples of a mammography CAD system are presented in U.S. Pat. Nos. 5,729,620 and 5,917,929, which are incorporated by reference herein. An example of a chest CAD system is presented in WO02/056240, which is incorporated by reference herein. It is to be appreciated that, although particular references to mammography and chest CAD system are provided infra, the scope of the preferred embodiments includes any of a variety of CAD systems that receive 2D or 3D medical images of a body part and detect, automatically or with manual assistance, anatomical abnormalities therein. Examples include colon CAD systems, bone CAD systems, and other CAD systems.
It is to be further appreciated that although particular reference to x-ray mammography and chest CT imaging modalities is provided infra, the scope of the preferred embodiments includes any of a variety of imaging modalities that, either presently or prospectively, (i) are amenable to CAD analysis, and (ii) are accommodated by the DICOM standard (or other medical imaging standard) from a CAD perspective. Prospective examples may include magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and ultrasound, as well as less conventional medical imaging modalities such as thermography, electrical conductivity-based modalities, etc.
Among the recent CAD-related additions to the DICOM standard are additional Information Object Definitions (IODs), including the Mammography CAD Structured Report (SR) IOD and the Chest CAD SR IOD (PS 3.3, Annexes A.35.5, A.35.6). The Mammography and Chest CAD SR IODs are used to convey the detection and analysis results of mammography and chest CAD systems, respectively. The content may include textual and a variety of coded information, numeric measurement values, references to the image data from which the CAD results were obtained, and spatial regions of interest within that referenced image data. The Mammography/Chest CAD SR IODs accommodate data not only for presentation to the clinician, but also data that may be solely for use in subsequent mammography/chest CAD analyses.
The contents and formatting of the Mammography and Chest CAD SR IODs are constrained according to CAD-related additions to PS 3.16 in the form of templates, and context groups for the coded terminology. For example, the Mammography CAD SR IOD is constructed according to the “Template ID (TID) 4000 Mammography CAD Document Root Template” which, in turn, can implicate subordinate templates as needed, the subordinate templates having names such as “TID 4001 Mammography CAD Overall Impression/Recommendation Template,” “TID 4009 Mammography CAD Individual Calcification Template,” “TID 4010 Mammography CAD Calcification Cluster Template,” and “TID 4011 Mammography CAD Density Template.” Likewise, the Chest CAD SR IOD is constructed according to the “TID 4100 Chest CAD Document Root Template” which, in turn, can implicate subordinate templates such as “TID 4101 Chest CAD Findings Summary Template,” “TID 4102 Chest CAD Composite Feature Template,” and “TID 4105 Chest CAD Descriptors.” Further information on the Mammography and Chest CAD SR IODs are provided in PS 3.3 at Annexes L and M, respectively.
Other additions to the DICOM standard made to accommodate CAD include the addition of specified Service-Object Pair (SOP) Classes. As known in the art, a SOP Class is a union of a specific set of DICOM Message Service Elements (DIMSEs) and a related IOD which completely defines a precise context for communication. For accommodation of CAD, there are now two Structured Reporting Storage SOP Classes—the Mammography CAD SR SOP Class and the Chest CAD SR SOP Class—instances of which transfer Mammography CAD SR Object Instances and Chest CAD SR Object Instances, respectively, from one device to another. (PS 3.4, Annexes B.5, O). There is also an additional Structured Reporting Media Storage SOP Class for each of the Mammography and Chest CAD SR IODs, instances of which are interchange and offline storage of Mammography CAD SR Object Instances and Chest CAD SR Object Instances, respectively (PS 3.4, Annex I). Finally, there are also additional SOP Class Unique Identifiers (UIDs) for the additional SOP Classes (PS 3.6, Annex A).
For clarity of presentation herein, where convenient, an information object (IO) or information object instance (IOI) shall be referred to independently of the SOP Class or SOP Instance of which they may be a part. The formation or presence of the appropriate SOP Class or SOP Instance can be inferred from the identity of the IO or IOI being described, together with the action being taken and/or the descriptive context. Also for clarity of presentation herein, where convenient, treatment of IOs or IOIs is without regard to their classification as normalized or composite, it being understood that their appropriate type, as well as the appropriate corresponding DIMSEs, SOP Classes, SOP Instances, etc., can be likewise inferred.
A typical configuration for a DICOM-based medical imaging system having CAD analysis features includes an image acquisition system (IAS), a CAD processing unit, and a viewing workstation (VWS). The IAS, CAD processing unit, and VWS are usually connected by a network, most commonly a TCP/IP based network, having sufficient bandwidth to accommodate transfer of medical images thereamong. The IAS is coupled to a physical image acquisition device (e.g., digital x-ray unit, CT unit, etc.) and receives the raw image data therefrom. The IAS populates the attributes of the relevant image information object, e.g., the Digital Mammography X-Ray Image Information Object or the CT Image Information Object, to form an instance of that object, which is generically referred to herein as a Source Image Information Object Instance (SI-IOI), it being understood that “Source” is substituted for the particular modality (“Digital X-Ray”, “CT”, etc.) as the preferred embodiments described herein extend to a variety of imaging modalities.
The SI-IOI is then transferred to the CAD processing unit, which performs CAD analysis on the digital image(s) contained in the SI-IOI. Based on the results of the CAD analysis, the CAD processing unit constructs the relevant CAD SR Information Object Instance (CAD SR-IOI), e.g., the Mammography CAD SR-IOI or the Chest CAD SR-IOI. The CAD SR-IOI is then transferred to the VWS. Depending on the particular system implementation, the original SI-IOI created by the IAS may be transferred directly from the IAS to the VWS or, alternatively, the original SI-IOI can accompany the CAD SR-IOI from the CAD processing unit to the VWS.
The VWS generates a display of the digital source image(s) contained in the SI-IOI, which are usually of diagnostic quality. The VWS also renders the CAD information contained in the CAD SR-IOI for presentation to a clinician. Rendering generally refers to the extraction of relevant CAD information from the CAD SR-IOI and the display of that information in a manner that facilitates clinician analysis of the medical image(s) upon which that CAD SR-IOI is based. In one known system, the VWS superimposes CAD markers and other CAD annotations derived from the CAD SR-IOI over the original digital images in the SI-IOI responsive to the clinician's pressing of a single toggle button. This provides a fast and easy method of offering a “second look” opportunity for the clinician in order to facilitate early detection of anatomical abnormalities.
A problem can arise, however, for market entrants or smaller enterprises seeking to market CAD processing units alone, their customers purchasing IAS and VWS units from other suppliers. More particularly, either presently or prospectively, a large enterprise having a substantial VWS market presence might harness that VWS market presence to bolster its share in the CAD processing unit market. In one scenario, this could be attempted by disabling the VWS from receiving and rendering CAD SR-IOIs, using either a software key or other disabling mechanism, unless the VWS customer also purchases their CAD processing unit from the VWS supplier. This effectively prevents the customer from purchasing their CAD processing unit from another source, because they would not be able to receive and view the results from the competing CAD processing unit in a DICOM-conforming manner. Rather, the customer would be required to view their CAD results in more awkward and workflow-inhibiting ways, such as by using paper CAD result printouts, or by placing an entirely additional CAD viewing workstation next to their VWS. This represents an undesirable scenario for the customer and, of course, for the provider of the competing CAD processing unit.
Another problem can be found in relation to new CAD processing capabilities as they arise, regardless of whether they are developed by a market entrant, a smaller enterprise, or a large existing enterprise. In particular, the ability of the DICOM standard to accommodate new CAD processing capabilities, in the form of appropriate CAD SR IODs, for example, can lag behind the introduction of the new CAD processing capabilities themselves. By way of example, while the DICOM standard may presently include Mammography CAD SR IODs and Chest CAD SR IODs, it may not presently include colon CAD SR IODs, bone CAD SR IODs, or, more generally, “anatomy X” SR IODs. By way of further example—although expected to be a less common scenario—a currently established CAD SR IOD might not yet accommodate a brand new form of CAD processing ability for that particular anatomical part, such as upon the discovery of new anatomical patterns shown to signify a future likelihood of disease. An enterprise wanting to market CAD processing units capable of the newest CAD capabilities would again be required to have their customers use the new machines in awkward and workflow-inhibiting ways, because existing the DICOM-conforming VWS units would not be capable of receiving and rendering the CAD results therefrom. Alternatively, the new CAD processing units and the existing VWS units would need private mutual modifications, most likely of the non-conforming variety, in order to accommodate transfer and rendering of the CAD results, which is generally undesirable in the long term.
Another problem can arise in that, even if the VWS manufacturer is not purposely attempting to disable CAD-related communication features, their VWS can simply be incompetently or erroneously designed, tested, and/or implemented such that structured reporting communications with the CAD processing unit are hindered. Also, for any of a variety of reasons, a given VWS installation may not be sufficiently backward-compatible or forward-compatible as needed to properly achieve the needed structured reporting communications with the CAD processing unit.
One known DICOM-based medical imaging system, developed prior to the adoption by the DICOM Standards Committee of general structured reporting including the above CAD SR IODs, uses the Radio Therapy Structured Set (RTSS) to communicate CAD results from a CAD processing unit to an VWS or other DICOM system. See R2 Technology, Inc., “DICOM Conformance Statement M1000-DM, V2.3A” (February 2001). However, as stated in a warning therein, “The use of RTSS by this device does not conform to the DICOM standard, as the data in the RTSS object is not radiotherapy related.” Accordingly, use of the RTSS to communicate CAD results from a CAD processing unit entails non-conforming operation of both the CAD processing unit and the VWS (or other destination device), which is generally undesirable in the long term.
Accordingly, it would be desirable to provide a method of doing business in which a CAD processing unit provider can integrate its CAD processing units into existing medical imaging systems in a DICOM-conforming manner, even where a VWS in the medical imaging system has had one or more of its DICOM CAD accommodations disabled for that CAD processing unit provider.
It would be further desirable to provide a medical imaging system in which CAD results are communicated, in a DICOM-conforming manner, from a CAD processing unit to a VWS for presentation to a clinician, even where the VWS cannot or will not properly receive or process any DICOM CAD structured reports, and/or a particular kind of DICOM CAD structured report, from the CAD processing unit.
It would be further desirable to provide a medical imaging system in which CAD results are communicated, in a DICOM-conforming manner, from a CAD processing unit to a VWS for presentation to a clinician, even where there is currently no mechanism to describe those CAD results using the current CAD accommodations of the DICOM standard, that is, when the DICOM CAD accommodations have not been amended or appended to cover the particular kind of CAD processing performed by the CAD processing unit.